Many of mobile terminals such as cellular phones, PDA's or mobile computers use a touch panel display as an input device for a user to input instructions or commands or data into the terminal. For example, the user can dial a phone number by touching numbers displayed on the touch panel display. Further, since the mobile terminals have a variety of functions other than a phone, the touch panel display has become a more important feature for the mobile terminals as an input device of the commands or instructions for the functions.
A lot of methods for operating the mobile terminal having a touch panel display for the user to input commands have been developed and reported. For example, U.S. Patent Publication Number US 2008/0165141 discloses various gestures for controlling, manipulating and editing of media files using touch sensitive devices. The gestures include tapping the display, spreading two fingers while simultaneously touching the display, sliding a finger on the display or drawing a circle on the display with the touch of a finger. These gestures are used to resize a window, scroll a display, rotate an object, zoom in/out of a displayed image, delete or insert text, etc.
One of the difficult commands to be input is zooming-in (enlarging) and zooming-out (shrinking) the displayed image on the display. In the above published patent application (US 2008/0165141), the gesture of spreading two fingers on the display is assigned to a zooming sequence. As illustrated by FIGS. 13A-13H of US 2008/0165141, when the user starts to spread the two fingers apart, the displayed map zooms in (enlarges).
One of the problems of this method is the user has to repeat the spreading gesture several times in order to get the desired size (magnification) of the map, because the fingers cannot be spread beyond the display. Apparently, when the user closes back the fingers together to shrink the map, the fingers cannot be closed anymore once they are closed. Accordingly, since the user has to repeat the spreading or closing gestures to get desired size of the map, it would take time to get a desired size of the map or other images. The method disclosed in US 2008/0165141 achieves only discrete and step-by-step zooming in/out of the displayed image, which is not a particularly intuitive method for zooming in/out the displayed image.
Another example of a conventional zooming-in/out function using a touch panel display is shown in a cellular phone model number HT-1100 for NTT Docomo in Japan manufactured by HTC Corporation in Taiwan. In the HT-1100 product, a user draws a circular figure in clockwise direction to zoom-in and in counter-clockwise to zoom-out. In this method, however, when the user draws one circular figure, then the image is enlarged or shrunk by one increment. Thus, the user has to draw another circle(s) if the magnification of the image is not sufficient. Similar to the method of US 2008/0165141, the HT-1100 product merely provides a discrete and step-by-step zooming in/out function of the displayed image, which is not an intuitive method for zooming in/out the displayed image.
Based on the above, there is a need for more intuitive method of inputting a zooming in/out command into a mobile terminal having a touch panel display.